There has been considerable speculation about the role of AI in genetic management of endangered cervid species in captivity, particularly as an aid to elimination of
inbreeding depression. AI allows for the insemination of females with semen of Ž
. unrelated males from distant populations Wildt, 1992; Holt et al., 1996 . While it seems
to have become fashionable to quote this as an outcome of any study on AI in cervids, in reality, specific research and practical applications are rare. Perhaps the best example of
the principle in practice is that of Eld’s deer in North American zoos, whereby hinds were inseminated laparoscopically with semen from males pre-selected on the basis of
Ž .
underrepresented genotype Monfort et al., 1993a .
6. Synchronisation of oestrus and AI
Ž .
The review of synchronisation of oestrus and AI of deer by Asher et al. 1993 provides considerable detail on procedures for red deer and fallow deer, species that
probably account for 95 of all inseminations performed in cervids. Recent studies on other cervid species have tended to use similar procedures to those established for
fallow deer. Inevitably, there must be considerable variation in response to treatment according to species, season, type of progestagen device used, and type and dose of
gonadotrophin used. However, there have been few extensive controlled experiments to evaluate the effects of these factors in most deer species, particularly with regard to
timing of oestrus and ovulation, which is particularly critical in AI programs with frozen–thawed semen.
6.1. Oestrous synchronisation Synchronisation of oestrus in deer has been generally adopted as a more efficient and
cost-effective alternative to detection of natural oestrous. As with other domestic ruminants, synchronisation can be achieved either by simulating the activity of the
corpus luteum through the administration of progestagens, or by shortening the luteal Ž
phase of the oestrous cycle by administration of a luteolysin prostaglandin F or its
2 a
. analogues . For some species such as fallow deer, it is also possible to obtain a high
degree of synchrony of a return oestrus after artificial synchronisation of the first oestrus Ž
. Asher and Thompson, 1989; Asher et al., 1986 .
A large number of studies have investigated the use of the CIDR device, containing progesterone, for efficacy of control of oestrous in deer. Intravaginal insertion of CIDR
devices for periods of between 12 and 14 days during the breeding season is generally effective in promoting a synchronised oestrus within 48 h of device withdrawal in fallow
Ž .
Ž .
deer Morrow et al., 1992 and red deer Asher et al., 1992b . This regimen has also Ž
. Ž
. proven successful for chital deer Mylrea, 1992 , Eld’s deer Monfort et al., 1993a and
Ž .
sambar deer Muir et al., 1997 . However, the additional administration of equine Ž
. chorionic gonadotrophin
eCG or PMSG at or near CIDR device withdrawal is
generally performed for red deer, particularly if synchronisation is attempted close to the Ž
. onset of the breeding season
Fennessy et al., 1990, 1991a . The use of eCG is contraindicated in fallow deer due to increased incidence of both anovulation and
Ž multiple ovulation, as well as fertilisation failure Asher and Smith, 1987; Jabbour et al.,
. 1993a .
A limited number of studies have investigated the efficacy of intravaginal sponges impregnated with either fluorogestone acetate or medroxyprogesterone acetate for
Ž .
control of oestrus and ovulation in red deer Kelly et al., 1982; Haigh et al., 1988 and Ž
. fallow deer Mulley et al., 1988 . While synthetic progestagens are able to control
ovulatory activity, some studies were plagued by excessive sponge loss, mitigating against their general effectiveness.
The ability of prostaglandins to synchronise oestrus is dependent on the presence of an active corpus luteum at the time of treatment, which limits synchronisation programs
to the period after the onset of natural ovulatory activity. Generally, the cervine corpus luteum is responsive to the exogenous prostaglandin during the latter half of the oestrous
cycle, although the precise timing of the transition from refractoriness to responsiveness
Ž .
has varied across studies on red deer, ranging from Day 6 Asher et al., 1995 to Day 11 Ž
. Fisher et al., 1994 . Oestrous synchronisation after injections of prostaglandin analogue
Ž .
Ž .
has been reported for red deer Asher et al., 1995 , wapiti Glover, 1985 , fallow deer Ž
. Ž
. Asher and Thompson, 1989; Jabbour et al., 1993a , PD’s deer Curlewis et al., 1988 ,
Ž .
Ž .
white-tailed deer Magyar et al., 1988 and reindeer Ropstad et al., 1996 . However, fertility of prostaglandin-induced ovulation has not been widely evaluated. In fallow
deer, administration of prostaglandin analogue was observed to induce tight synchrony Ž
. but poor fertility when compared with CIDR devices Jabbour et al., 1993a .
6.2. Insemination procedures Red and fallow deer together account for the vast majority of AIs performed in
cervids, particularly in New Zealand, Australia, USA and Canada. Laparoscopic intra- Ž
uterine insemination is presently the preferred method of AI in these two species Asher .
et al., 1993 , as it allows precise placement of relatively small quantities of semen close to the site of fertilisation and effective use of frozen–thawed semen. Detailed descrip-
Ž .
tions of the technique in deer are provided by Fennessy et al. 1991a,b and Haigh and Ž
. Ž
Bowen 1991 . Attempts at intravaginal Krzywinski and Jaczewski, 1978; Jabbour et .
Ž .
al., 1993a and transcervical intrauterine Asher et al., 1990a inseminations in red or Ž
. fallow deer have generally yielded variable, and often low - 40 , conception rates,
Ž .
especially with the use of frozen–thawed semen Asher et al., 1993 . Laparoscopic Ž
procedures have been adopted for other cervid species, including Eld’s deer Monfort et .
Ž .
Ž .
al., 1993a , axis deer Mylrea et al., 1992 and sambar deer Muir et al., 1997 .
7. Conclusion
